Robbiel and marmar4, I got help from wikipedia :Scree is a collection of broken rock fragments at the base of crags, mountain cliffs, volcanoes or valley shoulders that has accumulated through periodic rockfall from adjacent cliff facesFormation of scree or talus deposits results from physical and chemical weathering and erosional processes acting on a rock face. The predominant processes that degrade a rock slope depend largely on the regional climate (temperature, amount of rainfall, etc.). Many argue that a frost heaving process, like that known to act in soil in permafrost areas, may in fact play an important role in cliff degradation in cold environments.